Increasingly strict legal requirements for the permissible emissions of pollutants by motor vehicles, which are arranged in the internal combustion engines, make it necessary to keep emissions of pollutants as low as possible during the operation of the internal combustion engine. This can be done, on the one hand, by reducing emissions of pollutants which arise during the combustion of the air/fuel mixture in the respective combustion chamber of the cylinder of the internal combustion engine. On the other hand, exhaust gas post-treatment systems are used in internal combustion engines, said exhaust gas post-treatment systems converting the emissions of pollutants which are generated during the combustion process of the air/fuel mixture in the respective combustion chambers of the cylinders into harmless substances.
Internal combustion engines can be operated in various operating modes. For example, a homogeneous air/fuel mixture can therefore be generated with a air/fuel ratio which is approximately stoichiometric. Furthermore, the internal combustion engine can also be operated with a stratified charge of the air/fuel mixture in which a very lean mixture can be burnt in the combustion chamber by virtue of the fact that a stratified charge takes place in the vicinity of an ignition actuator.
In addition, the metering of fuel during a working cycle can also be divided into a plurality of partial injections in relation to a respective cylinder. Values of operating variables generally determine which of the operating modes the internal combustion engine is operated in. A suitable strategy during the selection of the operating modes makes it possible, on the one hand, to reduce emissions of pollutants, but on the other hand also allows possibly desired efficient operation of the internal combustion engine to be ensured.
Particularly great significance is accorded in this context to precise metering of the respective quantity of fuel which is to be metered by the respective injection valve. A particular demand in this context is a very high quantity spread of the required quantity of fuel which is to be metered by the respective injection valve.
For example, in the operating mode which is close to idling it is therefore possible to meter an extremely small quantity of fuel, while at full load of the engine it is possible to meter a very high quantity of fuel.